The present invention relates to a safety lock for securing the original lock nuts, hub and wheel bearings to the spindle of a dead axle trailer wheel or a dead axle tractor wheel in the event that they become loose.
These wheels have an inherent problem of coming off. The causes of this vary from poor maintenance, unsecured bearing locks, loss of oil causing bearing failure, and extreme loads causing bearing failure. In most cases, the falling off of the wheel is caused by a failed bearing or lock nuts, the lock nuts then unscrewing leaving nothing to hold the wheel on the spindle. Because of the nature of the thread on the outer end of the spindle, on which the lock nuts are fastened, the left side unscrews in forward motion and the right side unscrews during backing up.
In a reported accident resulting from bearing failure in Miami, Fla., on scene investigators concluded that the lack of maintenance, specifically proper lubrication, caused the wheel bearing to seize. They determined that the lack of grease on the wheel bearing, together with accumulated rust on the spindle and outside bearing, resulted in the following sequence:
a. The bearing progressively seized and overheated.
b. The bearing fused with the retaining washer and retaining lock nut.
c. This fused assembly started to rotate according to the forward wheel motion.
d. The lock tab on the retainer washer broke.
e. The cotter pin sheared off.
f. The fused assembly started to unscrew progressively until the complete wheel assembly became loose.
Of general background interest is Canadian Patent Application Serial No. 2,204,573 published Jun. 6, 1997, which describes and illustrates a plate secured to a hub, which bears against a portion of a wheel rim secured to the hub to prevent that rim from becoming unintentionally disassociated from the hub. U.S. Pat. Nos. 2,045,005, Whitacre; 3,523,709, Heggy et al; 3,623,761, Nadheray; 3,697,119, Van Wierst et al and 3,741,603, McLean, Jr. all describe and illustrate locking plates for axle end caps of railroad bearings, these locking plates bolted to the ends of their corresponding axles and bearing against the inner races of the bearings or associated wear rings for railway rolling stock.